Estrogen replacement therapy and the risk of endometrial cancer: remaining controversies.
To examine the relationship between exogenous estrogen administration and endometrial cancer, we used data from the Cancer and Steroid Hormone Study, a multicenter, population-based case-control study. Estrogen replacement therapy for greater than or equal to 2 years was associated with an increased risk of both localized and extrauterine cancer (relative risk = 2.8, 95% confidence limits 1.6, 4.6; relative risk = 2.9, 95% confidence limits 0.9, 9.4, respectively). However, the latter finding was based on a small number of cases in which estrogen was used. Women who underwent estrogen replacement therapy for greater than or equal to 2 years had significantly elevated risks of endometrial cancer (2.1 for 2 to 5 years and 3.5 for greater than or equal to 6 years). An elevated risk persisted for greater than or equal to 6 years after discontinuation of therapy. Women who exclusively used conjugated equine estrogen preparations less than or equal to 0.625 mg had no increased risk of endometrial cancer. A history of oral contraceptive use appeared to reduce the risk of endometrial cancer associated with estrogen replacement therapy. However, these latter two potentially important findings were based on a small number of cases in which hormones were used.
Rubin
G L
GL
Division of Reproductive Health, Centers for Disease Control, Atlanta, Georgia.
Peterson
H B
HB
Lee
N C
NC
Maes
E F
EF
Wingo
P A
PA
Becker
S
S
D000328:Adult; D016022:Case-Control Studies; D003276:Contraceptives, Oral / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors; D014594:Uterine Neoplasms / Q000139:chemically induced*
D003276:Contraceptives, Oral; D004967:Estrogens